The only screws you can adjust are the idle mixture.
Never bottom a screw in hard.
If it's a fresh rebuild that hasn't run 3 1/2 turns out from bottomed will generally get it to run.
If it's running; you do one screw at a time (if it has 2). Turn it in till it starts to run rough, out till it starts to run rough, then 1/2 way back.
If it has 2 screws, I would go back and forth several times till they're both in the optimium idle spot.
It's not about the fastest or slowest idle, it's about the best idle.